This invention relates to an apparatus for booms, preferably so-called self-expanding booms, which comprises a plate arranged on a platform, which plate is rotatable by means of a motor unit, and which comprises a means for winding-up the boom, which means is placed essentially vertically and essentially at the middle of the plate, and a means for feeding-in the boom, which means is arranged at an outer portion of the platform.
Such an apparatus is previously known from the granted Swedish patent application 429 143. This known apparatus has three guiding rolls placed on the platform itself at a distance from the means for winding up the boom, which rolls are connected together with the winding-up means by an overhead rod. This means that the known apparatus becomes unnecessarily expensive to manufacture.